Optical transceiver and method for automatically setting wavelength thereof

ABSTRACT

Provided is an optical transceiver including: a receiver configured to receive an optical transmission signal including wavelength information from another optical transceiver through a multiplexer/demultiplexer connected to the receiver; and a controller configured to identify a reception wavelength for communication with the other optical transceiver and to determine a wavelength corresponding to the reception wavelength as a transmission wavelength for communication with the other optical transceiver, based on the wavelength information included in the optical transmission signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.17/333,378 filed on May 28, 2021, which claims the benefit of KoreanPatent Application No. 10-2020-0064671, filed on May 29, 2020, andKorean Patent Application No. 10-2021-0066579, filed on May 25, 2021, inthe Korean Intellectual Property Office, the disclosures of which areincorporated herein in its entirety by reference.

BACKGROUND 1. Field

The present disclosure relates to an optical transceiver and a method ofautomatically setting a wavelength thereof.

2. Description of the Related Art

Wavelength-division multiplexing (WDM) is a technology that maysimultaneously transmit multiple optical signals through an identicaloptical fiber, which is achieved by making each optical signal have adifferent wavelength. On a transmitting side of a WDM-based opticalcommunication system, various optical signals of different wavelengthsare transmitted on the identical optical fiber. On a receiving side ofthe WDM-based optical communication system, the optical signals areseparated by wavelength. The advantage of a WDM system is that opticalfibers are efficiently used by allowing one optical fiber to carrymultiple optical signals having different carrier wavelengths.

In general, optical communication devices on the transmitting andreceiving sides constituting the WDM-based optical communication systemare located several to tens of kilometers apart from each other. Inaddition, a plurality of optical transceivers respectively correspondingto the optical communication devices are connected tomultiplexers/demultiplexers through an optical cable, so that theoptical communication devices on the transmitting and receiving sidesmay transmit and receive optical signals to each other at a remotelocation. For such optical communication, an optical link needs to beformed by setting a transmission wavelength and a reception wavelengthof each of the corresponding optical transceivers. However, it is verycumbersome and takes a long time for an administrator to visit theinstallation site of the optical communication devices and setwavelengths of the optical transceivers.

SUMMARY

Provided are an optical transceiver capable of automatically setting awavelength without an administrator's visit, and a method ofautomatically setting a wavelength of the optical transceiver

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to an aspect of the present disclosure, there is provided anoptical transceiver includes a receiver configured to receive an opticaltransmission signal including wavelength information from anotheroptical transceiver through a multiplexer/demultiplexer connected to thereceiver; and a controller configured to identify a reception wavelengthfor communication with the other optical transceiver and to determine awavelength corresponding to the reception wavelength as a transmissionwavelength for communication with the other optical transceiver, basedon the wavelength information included in the optical transmissionsignal.

According to an exemplary embodiment, the controller may determine awavelength corresponding to the reception wavelength as the transmissionwavelength using a pre-stored lookup table.

According to an exemplary embodiment, the controller may generatereception wavelength information about the reception wavelength andtransmission wavelength information about the transmission wavelength,and the optical transceiver may further include a transmitter configuredto generate and output an optical response signal including thereception wavelength information and the transmission wavelengthinformation.

According to an exemplary embodiment, the transmitter may generate theoptical response signal by superimposing an optical signal correspondingto the reception wavelength information and the transmission wavelengthinformation and an optical signal having a wavelength indicated by thetransmission wavelength information,

According to an exemplary embodiment, the optical signal correspondingto the reception wavelength information and the transmission wavelengthinformation and the optical signal having a wavelength indicated by thetransmission wavelength information may be optical signals of differentchannels.

According to an exemplary embodiment, the channel of the optical signalcorresponding to the reception wavelength information and thetransmission wavelength information may be an auxiliary management andcontrol channel (AMCC).

According to an aspect of the present disclosure, there is provided anoptical communication system includes a first optical transceiverconfigured to sequentially generate a plurality of optical transmissionsignals each including transmission wavelength information and to outputthe plurality of optical transmission signals to amultiplexer/demultiplexer connected to the first optical transceiver;and a second optical transceiver configured to receive any one of theplurality of optical transmission signals through a secondmultiplexer/demultiplexer connected to the firstmultiplexer/demultiplexer, to identify a reception wavelength forcommunication with the first optical transceiver based on wavelengthinformation included in any one of the optical transmission signals, andto determine a wavelength corresponding to the reception wavelength as atransmission wavelength for communication with the first opticaltransceiver.

According to an exemplary embodiment, the first optical transceiver maygenerate each of the plurality of optical transmission signals bysuperimposing an optical signal corresponding to the wavelengthinformation and an optical signal having a wavelength indicated by thewavelength information.

According to an exemplary embodiment, the second optical transceiver maydetermine a wavelength corresponding to the reception wavelength as thetransmission wavelength using a pre-stored lookup table.

According to an exemplary embodiment, the second optical transceiver maygenerate an optical response signal including reception wavelengthinformation about the reception wavelength and transmission wavelengthinformation about the transmission wavelength, and outputs the opticalresponse signal to the second multiplexer/demultiplexer.

According to an exemplary embodiment, the second optical transceiver maygenerate the optical response signal by superimposing an optical signalcorresponding to the reception wavelength information and thetransmission wavelength information and an optical signal having awavelength indicated by the transmission wavelength information.

According to an exemplary embodiment, the optical signal correspondingto the reception wavelength information and the transmission wavelengthinformation and the optical signal having a wavelength indicated by thetransmission wavelength information may be optical signals of differentchannels.

According to an exemplary embodiment, the channel of the optical signalcorresponding to the reception wavelength information and thetransmission wavelength information may be an auxiliary management andcontrol channel (AMCC).

According to embodiments of the present disclosure, wavelengths ofcorresponding optical transceivers may be automatically set without anadministrator's visit. Accordingly, it is possible to reducewavelength-related installation and maintenance costs as well as improveconvenience.

In addition, because there is no compatibility issue with an opticalcommunication device on which optical transceivers are mounted, andoptical transceivers including the same components may be used at bothends of a link, system construction costs may be reduced. Effectsobtainable by the embodiments of the disclosure are not limited to theeffects

described above, and other effects not described herein may be clearlyunderstood by one of ordinary skill in the art to which the inventiveconcept belongs from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the disclosure will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a schematic view of an optical communication system accordingto an embodiment;

FIG. 2 is a block diagram illustrating in more detail a main portion ofan optical transceiver in an optical communication system according toan embodiment;

FIG. 3 is a view of an exemplary optical communication system to explaina method of automatically setting a wavelength of an optical transceiveraccording to an embodiment;

FIG. 4 is a flowchart of a method of automatically setting a wavelengthof an exemplary optical transceiver; and

FIG. 5 is an exemplary diagram of a lookup table according to anembodiment.

DETAILED DESCRIPTION

Since the disclosure may have diverse modified embodiments, preferredembodiments are illustrated in the drawings and are described in thedetailed description. However, this is not intended to limit thedisclosure to particular modes of practice, and it is to be appreciatedthat all changes, equivalents, and substitutes that do not depart fromthe spirit and technical scope of the disclosure are encompassed in thedisclosure.

In the description of the disclosure, certain detailed explanations ofthe related art are omitted when it is deemed that they mayunnecessarily obscure the essence of the disclosure. In addition,numeral figures (e.g., first, second, and the like) used duringdescribing the specification are just identification symbols fordistinguishing one element from another element.

Further, in the specification, if it is described that one component “isconnected to” or “accesses” the other component, it is understood thatthe one component may be directly connected to or may directly accessthe other component but unless explicitly described to the contrary,another component may “be connected” or “access” between the components.In addition, terms including “unit,” “er,” “or,” “module,” and the likedisclosed in the

specification mean a unit that processes at least one function oroperation and this may be implemented by hardware or software such as aprocessor, a micro processor, a micro controller, a central processingunit (CPU), a graphics processing unit (GPU), an accelerated Processingunit (APU), a digital signal processor (DSP), an application specificintegrated circuit (ASIC), and a field programmable gate array (FPGA) ora combination of hardware and software.

In addition, it is intended to clarify that the division of thecomponents in the specification is only made for each main function thateach component is responsible for. That is, two or more components to bedescribed later below may be combined into one component, or onecomponents may be divided into two or more components according to moresubdivided functions. In addition, it goes without saying that each ofthe components to be described later below may additionally perform someor all of the functions of other components in addition to its own mainfunction, and some of the main functions that each of the components isresponsible for may be dedicated and performed by other components.

Hereinafter, various embodiments of the disclosure will be described indetail in order.

FIG. 1 is a schematic view of an optical communication system accordingto an embodiment, and FIG. 2 is a block diagram illustrating in moredetail a main portion of an optical transceiver in an opticalcommunication system according to an embodiment.

Referring to FIG. 1 , an optical communication system 10 according to anembodiment may include a first optical communication device 110including n first optical transceivers 1100-1 to 1100-n (n is a naturalnumber equal to or greater than 2), second optical communication devices120-1 to 120-n each including at least one second optical transceiver,and a multiplexer/demultiplexer 130 (hereinafter referred to asMUX/DEMUX). The first optical communication device 110 and the MUX/DEMUX130 may be connected to each other through an optical cable 141, and thesecond optical communication devices 120-1 to 120-nand the MUX/DEMUX 130may be connected to each other through a corresponding one of opticalcables 143-1 to 143-n. According to an embodiment, a plurality ofsub-MUXs/DEMUXs may be connected to the MUX/DEMUX 130, and a treetopology may be formed in such a way that the second opticalcommunication devices 120-1 to 120-n are connected to thesub-MUXs/DEMUXs.

In another embodiment, the optical communication system 100 mayconstitute an optical transport network, which is a sub-networkconstituting a fronthaul segment of a radio access network architecture.In this case, the optical communication device 110 may be a digital unit(DU) at a central office side or a termination device at a baseband unit(BBU) side. The second optical communication devices 120-1 to 120-n maybe a remote unit (RU) or a remote radio head (RRH). The MUX/DEMUX 130may be a remote node for dividing and combining optical signalstransmitted and received between the first optical communication device110 and the second optical communication devices 120-1 to 120-n.However, the disclosure is not limited thereto, and the inventiveconcept may be applied to midhaul and backhaul segments of the radioaccess network architecture.

In another embodiment, the optical communication system 10 may beapplied to an optical subscriber network. In this case, the firstoptical communication device 110 may be an optical line terminal (OLT)at the central office side. The second optical communication devices120-1 to 120-n may be any one of a remote terminal (RT), an opticalnetwork terminal (ONT) at a subscriber side, and an optical networkunit. The MUX/DEMUX 130 may be a remote node for dividing and combiningoptical signals transmitted and received between the first opticalcommunication device 110 and the second optical communication devices120-1 to 120-n.

In another embodiment, the optical communication system 10 may beapplied to a distributed antenna system (DAS) for solving a shadow areaof a base station. In this case, the first optical communication device120 may be a headend unit, and the second optical communication devices120-1 to 120-n and/or the MUX/DEMUX 130 may be an extension unit or aremote unit.

As described above, the optical communication system 100 according tothe inventive concept may be applied to various WDM-based opticalcommunication networks composed of optical communication devices thatare located remotely from each other and transmit and receive opticalsignals through corresponding optical transceivers.

Hereinafter, for convenience of description, an embodiment in which thefirst optical communication device 110 is a terminal device on the DUside and the second optical communication devices 120-1 to 120-n are RUswill be described on the premise that the optical communication system10 configures the fronthaul segment of the radio access networkarchitecture described above.

The first optical communication device 110 may generate in-band opticalsignals for use in transmitting high-speed data input from the DU side,multiplex the generated optical signals, and transmit them to theMUX/DEMUX 130 (based on downlink). Further, the first opticalcommunication device 110 may receive optical signals transmitted fromthe second optical communication devices 120-1 to 120-n through theMUX/DEMUX 130, and may perform certain signal processing on the receivedoptical signals and transmit the received optical signals to the DU side(based on uplink).

The first optical communication device 110 may include a main controller(MCU) 111, a memory 113, the n first optical transceivers 1100-1 to1100-n, and a MUX/DEMUX 115. The MCU 111 may be a component thatcontrols all operations of the first optical communication device 110.According to an embodiment, the MCU 111 may control a wavelength settingoperation for a wavelength to transmit and receive an optical signal toand from second optical transceivers 1200-1 to 1200-n of thecorresponding second optical communication devices 120-1 to 120-n of then first optical transceivers 1100-1 to 1100-n described later below.

The memory 113 may be connected to the MCU 111 and may store varioustypes of information and program instructions necessary for theoperation of the first optical communication device 110. For example,the memory 113 may store information about wavelengths of an opticalsignal allocated to the first optical communication device 110.

The first optical transceivers 1100-1 to 1100-n may bewavelength-tunable optical transceivers. Each of the first opticaltransceivers 1100-1 to 1100-n may perform an automatic wavelengthsetting operation of setting a transmission wavelength and a receptionwavelength to perform optical communication with each of the secondoptical transceivers 1200-1 to 1200-n of the corresponding secondoptical communication devices 120-1 to 120-n . The first opticaltransceivers 1100-1 to 1100-n may transmit optical signals to theMUX/DEMUX 115 using wavelengths determined as a result of the automaticwavelength setting operation, or receive optical signals from theMUX/DEMUX 115, respectively.

Each of the first optical transceivers 1100-1 to 1100-n may include afirst controller 1110, a first transmitter 1130, and a first receiver1150. Because respective functions and operations of the first opticaltransceivers 1100-1 to 1100-n are substantially the same, the firstoptical transceiver 1100-1 will be described as an example later below.

The first controller 1110 is configured to be connected to the MCU 111by wire or wirelessly, and may manage and control the first opticaltransceiver 1100-1.

The first controller 1110 may manage control necessary for smoothtransmission and reception of payload data between the first opticaltransceiver 1100-1 and a second optical transceiver correspondingthereto, for example, the second optical transceiver 1200-1 (control ofwavelength setting, etc. or control of communication status monitoring,etc.) and transmission and reception of information necessary for this(hereinafter referred to as control management data). For example, thefirst controller 1110 may control and manage wavelength tuning controlrequired for wavelength setting between the first optical transceiver1100-1 and the second optical transceiver 1200-1 corresponding thereto,transmission and reception of tuned optical signals, and generation andtransmission of information related to wavelengths of the transmittedand received optical signals.

Here, the first controller 1110 may be a term collectively referring toa processor that performs various control and processing to transmitlow-speed control management data as out-of-band optical signals throughan auxiliary management and control channel along with high-speedpayload data transmitted as in-band optical signals and/or a memory(e.g., 1111) in which firmware or the like is stored.

The first controller 1110 may transmit the control management data tothe second optical transceiver 1200-1 according to various methods. Forexample, the first controller 1110 may simultaneously transmit controlmanagement data and payload data to the second optical transceiver1200-1 through baseband intensity over-modulation. For another example,the first controller 1110 may superimpose the control management dataand the payload data and transmit the same to the second opticaltransceiver 1200-1 through a radio frequency (RF) pilot tone method.

The baseband intensity over-modulation is a technology in which thecontrol management data is stacked on top of the payload data, and theRF pilot tone method is a technology of superimposing ASK or FSKmodulated control management data with the payload data. A transmissionrate of the control management data may be different from a transmissionrate of the payload data. For example, a frequency of the controlmanagement data may be several kHz, and a frequency of the payload datamay be tens to hundreds of MHz. A control management datatransmission/reception method, such as the baseband intensityover-modulation and the RF pilot tone method, has already beendisclosed, and thus detailed contents thereof are omitted.

The first transmitter 1130 is configured to convert input payload dataand control management data into optical signals respectively andsuperimpose them. The first transmitter 1130 may include transmitteroptical sub-assemblies (TOSA) including a laser diode, a laser diodedriving circuitry (LDD), a biasing circuitry, and the like. The payloaddata input to the first transmitter 1130 may be input through the LDD.

The first receiver 1150 may divide an optical signal input from theMUX/DEMUX 115 by demultiplexing into payload data and control managementdata and output them in corresponding configurations, respectively. Inparticular, the first receiver 1150 may output the control managementdata to the first controller 1110. The first receiver 1150 may include areceiver optical sub-assembly (ROSA) including a photo diode and atrans-impedance amplifier (TIA), a post amplifier, and the like.

The MUX/DEMUX 115 may multiplex optical signals output from the firsttransmitter 1130 of each of the first optical transceivers 1100-1 to1100-n and transmit them to the optical cable 141, and may demultiplexoptical signals received by the optical cable 141. According to anembodiment, the MUX/DEMUX 115 may be a separate device separated fromthe first optical communication device 110.

N second optical communication devices 120-1 to 120-n may receiveoptical signals transmitted through the MUX/DEMUX 130 from the firstoptical communication device 110, photoelectrically convert the receivedoptical signals, and transmit the optical signals to users of a cellsite after certain signal processing (based on downlink). In addition,the second optical communication devices 120-1 to 120-n may generateoptical signals by electro-optically converting signals received fromusers, and transmit the generated optical signals to the MUX/DEMUX 130(based on uplink).

Each of the second optical communication devices 120-1 to 120-n mayinclude a corresponding optical transceiver from among n second opticaltransceivers 1200-1 to 1200-n. The second optical communication devices120-1 to 120-n may further include components for performing theabove-described signal processing in addition to the opticaltransceiver, and detailed descriptions will not be given herein forconvenience of description.

Each of the second optical transceivers 1200-1 to 1200-n may include asecond controller 1210, a second transmitter 1230, and a second receiver1250. Because respective functions and operations of the second opticaltransceivers 1200-1 to 1200-n are substantially the same, the secondoptical transceiver 1200-1 will be described as an example later below.

The second controller 1210 may be a component that controls alloperations of the second optical transceiver 1200-1.

The second controller 1210, similar to the first controller 1110described above, may manage control necessary for smooth transmissionand reception of payload data between the second optical transceiver1200-1 and the first optical transceiver 1100-1 corresponding thereto(control of wavelength setting, etc. or control of communication statusmonitoring, etc.) and transmission and reception of informationnecessary for this (hereinafter referred to as control management data).

For example, the second controller 1210 may control and managewavelength tuning control required for wavelength setting between thesecond optical transceiver 1200-1 and the first optical transceiver1100-1 corresponding thereto, transmission and reception of tunedoptical signals, and generation and transmission of information relatedto wavelengths of the transmitted and received optical signals.

Here, the second controller 1210 may be a term collectively referring toa processor that performs various control and processing to transmitlow-speed control management data as out-of-band optical signals throughan auxiliary management and control channel along with high-speedpayload data transmitted as in-band optical signals and/or a memory(e.g., 1211) in which firmware or the like is stored.

The second transmitter 1230 may be configured to correspond to the firsttransmitter 1130, and the second receiver 1250 may be configured tocorrespond to the first receiver 1150.

Optical signals corresponding to payload data and control managementdata may be generated and multiplexed through the second transmitter1230 and the MUX/DEMUX 130 and transmitted to the first opticaltransceiver 1100-1. An optical signal received from the first opticaltransceiver 1100-1 through the MUX/DEMUX 130 and the second receiver1250 may be demultiplexed and converted into an electrical signal.

In the above, the configuration of each of the first and second opticaltransceivers and all functions of each component have been described.Hereinafter, an operation of automatically setting a wavelength betweena first optical transceiver and a second optical transceivercorresponding to each other in the optical communication system 10 willbe described in detail with reference to FIGS. 3 to 5 .

FIG. 3 is a view of an exemplary optical communication system to explaina method of automatically setting a wavelength of an optical transceiveraccording to an embodiment, FIG. 4 is a flowchart of a method ofautomatically setting a wavelength of an exemplary optical transceiver,and FIG. 5 is an exemplary diagram of a lookup table according to anembodiment. FIG. 3 schematically shows the optical communication system10 shown in FIG. 1 centering on optical transceivers and MUXs/DEMUXs,and FIG. 4 shows an operation of a method of automatically setting awavelength between the first optical transceiver 1100-1 and the secondoptical transceiver 1200-1 of FIG. 3 from among the optical transceiversof FIG. 3 .

First, referring to FIG. 3 , the n first optical transceivers 1100-1 to1100-n may be connected to the MUX/DEMUX 115, then second opticaltransceivers 1200-1 to 1200-n may be connected to the MUX/DEMUX 130, andthe MUXs/DEMUXs 115 and 130 may be connected to each other through theoptical cable 141.

The first and second optical transceivers 1100-1 to 1100-n and 1200-1 to1200-n may be wavelength-tunable optical transceivers. Accordingly, thefirst and second optical transceivers 1100-1 to 1100-n and 1200-1 to1200-n may generate an optical signal by changing a wavelength accordingto a preset method.

For example, the first optical transceivers 1100-1 to 1100-n, accordingto wavelengths allocated to the first optical communication device 110on which the first optical transceivers 1100-1 to 1100-n are mounted,may generate optical signals having first to nt h wavelengths whilechanging the wavelengths to the first to n th wavelengths under thecontrol of the first controller 1110.

The second optical transceivers 1200-1 to 1200-n, according towavelengths allocated to the second optical communication devices 120-1to 120-n on which the second optical transceivers 1200-1 to 1200-n arerespectively mounted, may generate an optical signal having any one offirst to n th wavelengths under the control of the second controller1210. In this case, the second controller 1210 may analyze a wavelengthof an optical signal received from any one of the first opticaltransceivers 1100-1 to 1100-n, and may generate an optical signal havingany one of first to n^(th) wavelengths corresponding to the wavelengthof the received optical signal according to a result of the analyzing.An operation of selecting a wavelength of an optical signal by thesecond controller 1210 will be described later with reference to FIGS. 4and 5 .

The first optical transceivers 1100-1 to 1100-n may be connected to anarbitrary port of the MUX/DEMUX 115. In FIG. 3 , a case in which thefirst optical transceiver 1100-1 is connected to a first port Pcl, thefirst optical transceiver 1100-2 is connected to a second port Pc2, andthe first optical transceiver 1100-n is connected to an n th port Pcn isillustrated.

The second optical transceivers 1200-1 to 1200-n may be connected to anarbitrary port of the MUX/DEMUX 130. In FIG. 3 , a case in which thesecond optical transceiver 1200-1 is connected to a first port PR1, thesecond optical transceiver 1200-2 is connected to a second port PR2, andthe second optical transceiver 1200-n is connected to an n^(th) port PRnis illustrated.

Meanwhile, the MUX/DEMUX 115 may be set to transmit only an opticalsignal having a preset wavelength through each port through an opticalcable. For example, the first port Pc1 may be preset to transmit only anoptical signal having a first wavelength. In this case, all wavelengthspreset in the second port Pc2 to the n^(th) port Pcn may be different.This is the same in the case of the MUX/DEMUX 130 connected thereto.

Accordingly, among the first and second optical transceivers 1100-1 to1100-n and 1200-1 to 1200-n connected to the MUXs/DEMUXs 115 and 130,optical transceivers corresponding to each other need to set wavelengthsto communicate with each other using optical signals having a wavelengththat may be transmitted or received through a port to which they areconnected. To this end, the first and second optical transceivers 1100-1to 1100-n and 1200-1 to 1200-n according to an embodiment mayautomatically recognize a wavelength corresponding to a port to whichthey are connected, and perform an automatic wavelength settingoperation for setting a wavelength for communication with correspondingoptical transceivers.

The operations to be described later below may be operations performedin any one of the first optical transceivers 1100-1 to 1100-n and anyone of the second optical transceivers 1200-1 to 1200-n. The two opticaltransceivers performing the operations may be optical transceiverscapable of transmitting and receiving optical signals to each other byforming an optical link connection. Hereinafter, it is assumed that thefirst optical transceiver 1100-1 and the second optical transceiver1200-1 form an optical link connection with each other.

Referring to FIG. 4 , in operation S410, the first optical transceiver1100-1 may generate first to n^(th) optical transmission signals havingfirst to n^(th) wavelengths and output them to the MUX/DEMUX 115. Here,the first to nth optical transmission signals may include transmissionwavelength information about each wavelength (i.e., a correspondingwavelength from among the first to n^(th) wavelengths).

The first to n^(th) wavelengths and transmission wavelength informationcorresponding thereto may be preset to perform an automatic wavelengthsetting operation, and setting values may be stored in a memory 1111 ofthe first controller 1110. However, the disclosure is not limitedthereto, and the setting values may be stored in the memory 113 of thefirst optical communication device 110. Alternatively, the settingvalues may be transmitted to the first controller 1110 from the MCU 111or from an external management server (not shown), a local terminal, orthe like through the MCU 111.

The transmission wavelength information is information about a length ofa corresponding wavelength, and may be information generated as controlmanagement data by the first controller 1110. For example, for a firstoptical transmission signal having a first wavelength, the firstcontroller 1110 may generate information about a length of the firstwavelength as control management data.

The first transmitter 1130 may generate optical signals having first ton th wavelengths (test optical signals), may generate an optical signal(control management optical signal) corresponding to transmissionwavelength information indicating each of the first to nth wavelengthsunder control of the first controller 1110, may generate opticaltransmission signals by sequentially superimposing a test optical signaland a control management optical signal corresponding to each other, andoutput the generated optical transmission signals to the MUX/DEMUX 115.

In operation S420, the second optical transceiver 1200-1 may receiveonly an mth optical transmission signal from among the first to n thoptical transmission signals through the MUX/DEMUX 115, the opticalcable 141, and the MUX/DEMUX 130.

As described above, because each port of the MUX/DEMUX 115 performs thefunction of a band pass filter (BPF) so that only optical signals of apreset wavelength may be output, one of the first to nt h opticaltransmission signals, for example, only the m^(th) optical transmissionsignal (m is a natural number equal to or less than n) may betransmitted to the second optical transceiver 1200-1 through the opticalcable 141 and the MUX/DEMUX 130 through the first port Pc1 to which thefirst optical transceiver 1100-1 is connected.

In operation S430, the second receiver 1250 of the second opticaltransceiver 1200-1 may output m^(th) transmission wavelength informationincluded in the m^(th) optical transmission signal to the secondcontroller 1210, and the second controller 1210 may analyze the m^(th)transmission wavelength information to identify an m th wavelength. Thatis, the second controller 1210 may identify the wavelength of an opticalsignal that the second optical transceiver 1200-1 may receive from thefirst optical transceiver 1100-1 as the m^(th) wavelength.

In operation S440, the second optical transceiver 1200-1 may identify atransmission wavelength corresponding to an identified receptionwavelength using a lookup table stored in the memory 1211. The lookuptable is a table obtained by pre-matching a reception wavelength and atransmission wavelength corresponding to each other in consideration ofallocated wavelengths for each port of MUXs/DEMUXs, and may be updatedaccording to the use environment of optical transceivers. In moredetail, the second controller 1210 may use the lookup table to identifythat a transmission wavelength matched with the m^(th) wavelength thatis a reception wavelength is a p th wavelength. When the identifiedreception wavelength is an a^(th) wavelength, the second controller 1210may read an α^(th) wavelength matched with the a^(th) wavelength as atransmission wavelength (see FIG. 5 ) Likewise, when the identifiedreception wavelength is a bth wavelength, the second controller 1210 mayread a β^(th) wavelength matched with the bth wavelength as atransmission wavelength (see FIG. 5 ).

In operation S450, the second optical transceiver 1200-1 may generate anoptical response signal having a p^(th) wavelength in response to them^(th) optical transmission signal and output the optical responsesignal to the MUX/DEMUX 130. The optical response signal may includetransmission wavelength information about the p^(th) wavelength. Inaddition, the optical response signal may further include receptionwavelength information about a reception wavelength (e.g., an m^(th)wavelength) of the second optical transceiver 1200-1 identified inoperation S430.

The transmission wavelength information is information about a length ofa corresponding wavelength, and may be information generated as controlmanagement data by the second controller 1210. For example, for anoptical response signal having a p^(th) wavelength, the secondcontroller 1210 may generate information about a length of the p thwavelength as control management data (e.g., auxiliary management andcontrol channel (AMCC) data).

In addition, the reception wavelength information is information about alength of a corresponding reception wavelength, and may be informationgenerated as control management data by the second controller 1210. Forexample, when the reception wavelength is an m^(th) wavelength, thesecond controller 1210 may generate information about a length of thesecond wavelength as control management data (e.g., AMCC data).

In addition, the second transmitter 1230 may generate an optical signalhaving a p th wavelength (a test optical response signal), may generatean optical signal (control management optical signal) corresponding totransmission wavelength information and/or reception wavelengthinformation under control of the second controller 1210, may generatethe optical response signal by superimposing the generated test opticalresponse signal and control management optical signal, and may outputthe generated optical response signal to the MUX/DEMUX 130.

In operation S460, the first optical transceiver 1100-1 may receive theoptical response signal through the MUX/DEMUX 130, the optical cable141, and the MUX/DEMUX 115. Each port of the MUX/DEMUX 130 performs thefunction of a BPF so that outputs only an optical signal of a presetwavelength, but because the second optical transceiver 1200-1 transmitsthe optical response signal having a wavelength capable of passingthrough a port PR1, the optical response signal may be transmitted tothe first optical transceiver 1100-1 through the MUX/DEMUX 115.

In operation S470, the first receiver 1150 of the first opticaltransceiver 1100-1 may output transmission wavelength information andreception wavelength information included in the optical response signalto the first controller 1110. The first controller 1110 may analyze thetransmission wavelength information and the reception wavelengthinformation to identify that a wavelength that the first opticaltransceiver 1100-1 may receive from the second optical transceiver1200-1 is a p^(th) wavelength and a wavelength that the first opticaltransceiver 1100-1 may transmit to the second optical transceiver 1200-1is an m^(th) wavelength.

In operation S480, the first controller 1110 may generate optical linkinformation between the first optical transceiver 1100-1 and the secondoptical transceiver 1200-1 including information about the identifiedtransmittable wavelength and receivable wavelength (i.e., the m^(th)wavelength and the p^(th) wavelength), and the first controller 1110 andthe first transmitter 1130 may generate an out-of-band optical signalcorresponding to the generated optical link information (as controlmanagement data, e.g., AMCC data), and transmit the out-of-band opticalsignal to the second optical transceiver 1200-1 through the MUX/DEMUX115, the optical cable 141, and the MUX/DEMUX 130. The second opticaltransceiver 1200-1 may also recognize that the wavelength settingoperation is terminated by receiving the optical link information.

By the above-described operation, the first optical transceiver 1100-1and the second optical transceiver 1200-1 may perform opticalcommunication by automatically recognizing and setting wavelengths thatmay be transmitted/received to each other.

As described above, in the optical communication system 10 according toan embodiment, wavelength-tunable optical transceivers corresponding toeach other at a transmitting side and a receiving side may automaticallyperform a wavelength setting operation for optical communication withoutdirect adjustment such as an administrator's visit. Accordingly, it ispossible to reduce costs as well as improve the convenience ofinstallation, maintenance, and management.

In addition, the optical transceivers are versatile because there is nocompatibility issue with an optical communication device to which theoptical transceivers are applied, and the wavelength-tunable opticaltransceivers on both sides may have substantially the same components,so that the cost of building a system may be greatly reduced.

While the embodiments have been particularly shown and described, itwill be understood by one of ordinary skill in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims.

What is claimed is:
 1. An optical transceiver comprising: a receiverconfigured to receive an optical transmission signal includingwavelength information about a wavelength of the optical transmissionsignal from another optical transceiver through amultiplexer/demultiplexer connected to the receiver; and a controllerconfigured to identify a reception wavelength for communication with theother optical transceiver and to determine a transmission wavelength forcommunication with the other optical transceiver, based on thewavelength information included in the optical transmission signal,wherein the optical transmission signal is one of a plurality of opticaltransmission signals which are generated for the optical transceiver,have different wavelengths, and are sequentially output from the otheroptical transceiver, and the optical transmission signal is selected anddelivered to the optical transceiver among the plurality of opticaltransmission signals by the multiplexer/demultiplexer.
 2. The opticaltransceiver of claim 1, wherein the controller determines thetransmission wavelength using a pre-stored lookup table.
 3. The opticaltransceiver of claim 1, wherein the controller generates receptionwavelength information about the reception wavelength and transmissionwavelength information about the transmission wavelength, and theoptical transceiver further comprises: a transmitter configured togenerate an output an optical response signal including the receptionwavelength information and the transmission wavelength information. 4.The optical transceiver of claim 3, wherein the transmitter generatesthe optical response signal by superimposing an optical signal includingthe reception wavelength information and the transmission wavelengthinformation and an optical signal having the transmission wavelength. 5.The optical transceiver of claim 4, wherein the optical signal includingthe reception wavelength information and the transmission wavelengthinformation and the optical signal having the transmission wavelengthare optical signals of different channels.
 6. The optical transceiver ofclaim 5, wherein a channel of the optical signal including the receptionwavelength information and the transmission wavelength information is anauxiliary management and control channel (AMCC).
 7. An opticalcommunication system comprising: a first optical transceiver configuredto sequentially generate a plurality of optical transmission signals ofdifferent wavelengths, each optical transmission signal includingtransmission wavelength information about a wavelength of the opticaltransmission signal, and to output the plurality of optical transmissionsignals to a first multiplexer/demultiplexer connected to the firstoptical transceiver; and a second optical transceiver configured toreceive one of the plurality of optical transmission signals through asecond multiplexer/demultiplexer connected to the firstmultiplexer/demultiplexer, to identify a reception wavelength forcommunication with the first optical transceiver based on wavelengthinformation included in the one of the optical transmission signals, andto determine a transmission wavelength for communication with the firstoptical transceiver based on the wavelength information included in theone of the optical transmission signals, wherein the plurality ofoptical transmission signals are generated for the second opticaltransceiver.
 8. The optical communication system of claim 7, wherein thefirst optical transceiver generates each of the plurality of opticaltransmission signals by superimposing an optical signal including thewavelength information and an optical signal having a wavelengthindicated by the wavelength information.
 9. The optical communicationsystem of claim 7, wherein the second optical transceiver determines thetransmission wavelength using a pre-stored lookup table.
 10. The opticalcommunication system of claim 7, wherein the second optical transceivergenerates an optical response signal including reception wavelengthinformation about the reception wavelength and transmission wavelengthinformation about the transmission wavelength, and outputs the opticalresponse signal to the second multiplexer/demultiplexer.
 11. The opticalcommunication system of claim 10, wherein the second optical transceivergenerates the optical response signal by superimposing an optical signalincluding the reception wavelength information and the transmis sionwavelength information and an optical signal having the transmissionwavelength.
 12. The optical communication system of claim 11, whereinthe optical signal including the reception wavelength information andthe transmission wavelength information and the optical signal havingthe transmission wavelength are optical signals of different channels.13. The optical communication system of claim 12, wherein a channel ofthe optical signal including the reception wavelength information andthe transmission wavelength information is an auxiliary management andcontrol channel (AMCC).
 14. An optical transceiver comprising: atransmitter configured to sequentially transmit a plurality of opticaltransmission signals of different wavelengths to amultiplexer/demultiplexer connected to the optical transceiver; areceiver configured to receive an optical response signal includingtransmission wavelength information and reception wavelength informationfrom another optical transceiver through the multiplexer/demultiplexer;and a controller configured to generate optical link information betweenthe optical transceiver and the other optical transceiver based on thetransmission wavelength information and the reception wavelengthinformation, wherein the transmission wavelength information includesinformation on one of the different wavelengths which passes themultiplexer/demultiplexer, and the reception wavelength informationincludes information on a wavelength matched to the one of the differentwavelengths of which an optical signal transmitted from the otheroptical transceiver.
 15. The optical transceiver of claim 14, whereinthe controller is configured to sequentially generate each of theplurality of optical transmission signals of different wavelengths bysuperimposing a control management optical signal including wavelengthinformation and a test optical signal having a wavelength indicated bythe wavelength information.
 16. The optical transceiver of claim 15,wherein the control management optical signal and the test opticalsignal are transmitted through different channels.
 17. The opticaltransceiver of claim 16, wherein the control management optical signalis transmitted through an auxiliary management and control channel(AMCC).